Wiemer E A, Hannaert V, van den IJssel P R, Van Roy J, Opperdoes F R, Michels P A
International Institute of Cellular and Molecular Pathology, Research Unit for Tropical Diseases, Brussels, Belgium.
J Mol Evol. 1995 Apr;40(4):443-54. doi: 10.1007/BF00164030.
In Trypanoplasma borelli, a representative of the Bodonina within the Kinetoplastida, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity was detected in both the cytosol and glycosomes. This situation is similar to that previously found in Trypanosomatidae, belonging to a different Kinetoplastida suborder. In Trypanosomatidae different isoenzymes, only distantly related, are responsible for the activity in the two cell compartments. In contrast, immunoblot analysis indicated that the GAPDH activity in cytosol and glycosomes of T. borelli should be attributed to identical or at least very similar proteins related to the glycosomal GAPDH of Trypanosomatidae. Moreover, only genes related to the glycosomal GAPDH genes of Trypanosomatidae could be detected. All attempts to identify a gene related to the one coding for the trypanosomatid cytosolic GAPDH remained unsuccessful. Two tandemly arranged genes were found which are 95% identical. The two encoded polypeptides differ in 17 residues. Their sequences are 72-77% identical to the glycosomal GAPDH of the other Kinetoplastida and share with them some characteristic features: an excess of positively charged residues, specific insertions, and a small carboxy-terminal extension containing the sequence -AKL. This tripeptide conforms to the consensus signal for targeting of proteins to glycosomes. One of the two gene copies has undergone some mutations at positions coding for highly conserved residues of the active site and the NAD(+)-binding domain of GAPDH. Modeling of the protein's three-dimensional structure suggested that several of the substitutions compensate each other, retaining the functional coenzyme-binding capacity, although this binding may be less tight. The presented analysis of GAPDH in T. borelli gives further support to the assertion that one isoenzyme, the cytosolic one, was acquired by horizontal gene transfer during the evolution of the Kinetoplastida, in the lineage leading to the suborder Trypanosomatina (Trypanosoma, Leishmania), after the divergence from the Bodonina (Trypanoplasma). Furthermore, the data clearly suggest that the original GAPDH of the Kinetoplastida has been compartmentalized during evolution.
在动质体目波豆亚目的代表物种博氏锥体虫中，在胞质溶胶和糖体中均检测到甘油醛-3-磷酸脱氢酶（GAPDH）活性。这种情况与先前在属于不同动质体目亚目的锥虫科中发现的情况相似。在锥虫科中，不同的同工酶（仅远缘相关）负责两个细胞区室中的活性。相比之下，免疫印迹分析表明，博氏锥体虫胞质溶胶和糖体中的GAPDH活性应归因于与锥虫科糖体GAPDH相同或至少非常相似的蛋白质。此外，只能检测到与锥虫科糖体GAPDH基因相关的基因。所有鉴定与编码锥虫胞质GAPDH的基因相关基因的尝试均未成功。发现了两个串联排列的基因，它们的同源性为95%。这两个编码的多肽在17个残基上有所不同。它们的序列与其他动质体目的糖体GAPDH的序列同源性为72-77%，并与它们共享一些特征：带正电荷的残基过量、特定插入以及包含序列-AKL的小羧基末端延伸。这个三肽符合蛋白质靶向糖体的共有信号。两个基因拷贝之一在编码GAPDH活性位点和NAD(+)结合域高度保守残基的位置发生了一些突变。蛋白质三维结构建模表明，一些取代相互补偿，保留了功能性辅酶结合能力，尽管这种结合可能不那么紧密。对博氏锥体虫GAPDH的分析进一步支持了这样的观点，即在动质体目的进化过程中，在与波豆亚目（锥体虫）分化后，在导致锥虫亚目（锥虫、利什曼原虫）的谱系中，一种同工酶，即胞质同工酶，是通过水平基因转移获得的。此外，数据清楚地表明，动质体目的原始GAPDH在进化过程中已被区室化。
